Upgrade to ASM 5.0-beta

Start using ASM 5.0 in preparation for add JDK 1.8 support to
JiteScript.

Signed-off-by: Pekka Enberg <penberg@iki.fi>
Add JDK 1.8 version support

Signed-off-by: Pekka Enberg <penberg@iki.fi>
Merge pull request #8 from penberg/jdk8

Add JDK8 version support